1. Field of the Invention
The present invention relates to a display device, and in particular to a display device having an illuminator as well as a driving method for the same. The present invention also relates to an instrument panel and an automotive vehicle having such a display device.
2. Description of the Related Art
In recent years, on the strength of being thin and consuming little power, liquid crystal display devices have been broadly used in laptop personal computers, mobile phones, camera-incorporated VTRs having a liquid crystal monitor, etc.
A liquid crystal display device is not a self-light-emitting display device which is capable of emitting light by itself, unlike a CRT (cathode-ray tube) or an EL (electroluminescent) display device. Therefore, a liquid crystal display device includes an illuminator (called a backlight) provided at the rear face side of a liquid crystal display panel, and performs displaying by utilizing light from this backlight.
As a light source for backlighting, a cold-cathode tube has often been used conventionally. Recently, from the standpoint of environmental concerns and the like, there are increased needs for mercury-free constructions, and thus use of an LED (light-emitting diode) as a light source for backlighting has been proposed.
However, LEDs are currently inferior to cold-cathode tubes in terms of efficiency of optical conversion. Therefore, using an LED to realize a high luminance similar to that of a cold-cathode tube would result in an increased power consumption.
As a technique for solving this problem, Patent Document 1 discloses a technique of enhancing the efficiency of light utility by providing a reflection-type polarizer between an illuminator and a liquid crystal display panel, thus allowing for lower power consumption.
[Patent Document 1] Japanese Laid-Open Patent Publication No. 11-202781
However, depending on the purpose, a liquid crystal display device is required to have a very superbly low power consumption, so that even the technique disclosed in Patent Document 1 may not provide a desired level of low power consumption.